Tracing Stellar Mergers with Chemistry: Carbon Isotopes Reveal Clues to Mysterious Stars

Astronomers studied massive α-enriched (MAE) stars, which look chemically old but appear too massive to be ancient. By measuring carbon isotope ratios (¹²C/¹³C), Zachary Maas and collaborators found most MAE stars resemble thick disk stars, while a few show evidence of mass transfer or mergers. The results suggest MAE stars form through multiple pathways, with carbon isotopes serving as key clues to their hidden histories.